2016年6月大学英语四级考试模拟题及答案(7)

　　The immune system can be mimicked and tested, too. ProBioGen, a company based in Berlin, is developing an artificial human lymph node (淋巴结) which, it reckons, could have prevented the neardisastrous consequences of a drag trial held in Britain three months ago, in which (despite the drag having passed animal tests) six men suffered multiple organ failure and nearly died. The drug the men were given made their immune systems hyperactive. Such a response would, the firm's scientists reckon, nave teen identified by their lymph node, which is made from cells that provoke the immune system into a response. ProBioGen's lymph node could thus work better than animal testing. A second alternative

　　Another way of cutting the number of animal experiments would be to change the way that vaccines are tested, according to Coenraad Hendriksen of the Netherlands Vaccine Institute. At the moment, all batches of vaccine are subject to the same battery of tests. Dr. Hendriksen argues that this is over-rigorous. When new vaccine cultures are made, belt-and-braces tests obviously need to be applied. But if a batch of vaccine is derived from an existing culture, he suggests that it need be tested only to make sure it is identical to the batch from which it is derived. That would require fewer test animals.

　　All this suggests that though there is still some way to go before drugs, vaccines and other substances can be tested routinely on cells rather than live animals, useful progress is being made. What is harder to see is how the use of animals might be banished from fundamental research. Weighing the balance

　　In basic scientific research, where the object is to understand how, say, the brain works rather than to develop a drug to treat brain disease, the whole animal is often necessarily the object of study. Indeed, in some cases, scientific advances are making animal tests more valuable, rather than less. Geneticmodification techniques mean that mice and rats can be remodelled to make them exhibit illnesses that they would not normally suffer from. Also, genes for human proteins can be added to them, so that animal tests will more closely mimic human responses. This offers the opportunity to understand human diseases better, and to screen treatments before human trials begin. However, the very creation of these mutants (突变异种) counts as an animal experiment in its own right, so the number of experiments is increasing once again.

　　What is bad news for rodents, though, could be good news for primates. Apes and monkeys belong to the same group of mammals as humans, and are thus seen as the best subjects for certain sorts of experiment. To the extent that rodents can be "humanised", the number of primate experiments might be reduced.

　　Some people, of course, would like to see them eliminated altogether, regardless of the effect on useful research. On June 6th the British Union for the Abolition of Vivisection, an animal-rights group, called for the use of primates in research to be banned. For great apes, this has already happened. Britain, Austria, the Netherlands, New Zealand and Sweden have ended experiments on chimpanzees, gorillas, bonobos and orang-utans. Experiments on monkeys, though, are still permitted. And some countries have not banned experiments on apes. In America, for example, about 1,000 chimpanzees a year are used in research.

　　This is a difficult area. Great apes are man's closest relatives, having parted company from the human family tree only a few million years ago. Hence it can be (and is) argued that they are indispensable for certain sorts of research. On the other hand, a recent study by Andrew Knight and his colleagues at Animal Consultants International, an animal-advocacy group, casts doubt on the claim that apes are used only for work of vital importance to humanity. Important papers tend to get cited as references in subsequent studies, so Mr. Knight looked into the number of citations received by 749 scientific papers published as a result of invasive experiments on captive chimpanzees. Half had received not a single citation up to ten years after their original publication.

　　That is damning. Animal experiments are needed for the advance of medical science, not to mention people's

　　safety. But if scientists are to keep the sympathy of the public, they need to do better than that.

　　1. The passage summarizes harmful effects of animal experiment. However, as animal experiment is indispensable in a number of areas, it might not be stopped or replaced by other alternatives.